Leads implanted in or about the heart have been used to reverse certain life threatening arrhythmia, or to stimulate contraction of the heart. Electrical energy is applied to the heart via electrodes on the leads to return the heart to normal rhythm.
For example, atrial pacing is accomplished by locating an electrode in the right atrium. However, right atrium pacing and sensing can produce deleterious left heart timing intervals. One technique to apply an energy pulse to the left atrium of the heart is to implant the electrode through the coronary sinus to reach a location below the left atrium. However, it can be difficult to locate the coronary sinus ostium, thus implantation time can be excessive, or the procedure can be unsuccessful. Also, if it desired to apply electrical pulses to both the left atrium and right atrium, two leads may be needed.